Method and arrangement for completion or recovery of data transactions in a flash type memory device using a commit process

ABSTRACT

The invention relates to a method and arrangement for processing transactions in a flash type memory device, wherein the transaction is a data update and/or changing operation consisting of one or more suboperations, all of which must be successfully executed in order to regard the discussed transaction as having been successfully completed in its entirety. In the solution according to the invention, memory-block specific status information ( 131 ) of a memory block present in a flash type memory device is utilized not only for managing payload data ( 141 ) present in the memory block but also for the management of an entire transaction. Consequently, there is no need for a separate status bookkeeping of transactions, thus reducing the number of reading and writing operations required in transactions.

FIELD OF THE INVENTION

The invention relates to a method for processing transactions in a flashtype memory device, wherein the transaction Is a data update and/orchanging operation consisting of one or more suboperations, all of whichmust be successfully executed in order to regard the discussedtransaction as having been successfully completed In its entirety. TheInvention relates also to an arrangement for processing transactions ina flash type memory device.

BACKGROUND OF THE INVENTION

The concept of transaction is used in the maintenance of suchinformation systems in which the pieces of information stored in thesystem must be compatible or non-contradictory with each other at everytime instant. One conceivable example is a banking application, whereina given bank account involves information such as a balance and accounttransactions. Assuming an exemplary situation, wherein the informationregarding account transactions would have had recorded therein an entryrepresenting a deposit or withdrawal transaction, but updating theaccount balance information has not been managed yet. If, at this point,the information system was to fall into an error condition, i.e. tocrash, the restart procedure would possibly create a situation in whichthe sets of information regarding the bank account would have a mutualdiscrepancy therebetween: the balance information and the informationregarding account transactions would not comply with each other. Theoccurrence of a mismatch as described above can be avoided in such a waythat the operations relevant to information stored in the system beprocessed as suboperations included in a single data processing entityor transaction, all of which must be successfully executed in order forsaid transaction to be considered successfully completed. In the eventthat all suboperations have not become successfully executed, none ofthe suboperations is considered as executed. In the foregoing exemplarysituation, this means that for example a new transaction entry is notvalid until after a matching update has been made in balance informationand both the transaction entry and the updated balance information haveeach been validated simultaneously.

In this document, the concept of transaction is used in reference to adata processing entity constituted by one or more suboperations, whereinall suboperations must be successfully executed for a transaction to beregarded as successfully completed. The transaction is usually dividedinto three successive operations: a start of transaction, an update ofdata, and a commitment of transaction. The update of data compriseschanging existing data, deleting existing data, and adding new data. Thecommitment refers to processing the updated data into valid data. Thedata, for whose changing, deletion or addition a transaction isexecuted, is in this document referred to as payload data. Valid payloaddata prior to the commitment of a transaction consists of that payloaddata which is consistent with the condition prior to starting thetransaction. In a recovery process subsequent to a serious systemmalfunction (for example a system crash), which has taken place during atransaction, said transaction shall be concluded provided that the startof a commitment process has been reached, i.e. all updates have beenmanaged. If this is not the case, not a single update relevant to thetransaction shall be validated.

Sets of hardware used for implementing information systems are oftenprovided with two types of memory: a non-volatile memory and a volatilememory. The information present in a non-volatile memory is availablefor service in a recovery process subsequent to a serious system error.On the other hand, the information present in a volatile memory isusually lost in the occurrence of a serious system error. The situationdiscussed in this document is such that the non-volatile memory isimplemented by way of a flash type memory device. A typical feature insemiconductor flash memory circuits is that data present in the memorycannot generally be updated in one physical storage location withoutfirst erasing away an entire memory block. After a block-level erasion,all bits of the erased memory block have a common value, which isusually ‘1’. Each bit of the memory block can be changed thereafterseparately for another value, which is usually ‘0’. After this, the onlyway of changing the value a discussed bit is to erase the entire memoryblock away again.

In this document, the term “flash type memory device” is used inreference to a memory device designed with one or more semiconductorflash memory circuits or to a logical flash memory device or LFMD deviceadapted to function according to the typical features of semiconductorflash memory circuits. For example, a magnetic diskette drive or astatic RAM device (Random Access Memory) can be adapted to function thesame way as an LFMD device. In addition, the flash type memory devicecan be a medium which has a semiconductor flash memory circuit linked toa memory device configured with other technology, such as a magneticdiskette drive or a static RAM device.

PRIOR ART

Publication WO0131458 “Method and arrangement for performing atomicupdates using a logical flash memory device” discloses a solution,wherein the processing of a transaction in a flash type memory device iseffected by using a transaction-specific identifier variable, expressingthat the transaction is not finished. Said identifier variable is storedin a flash type memory device, such that the information contained insaid identifier variable would not be lost in a possible system error.The identifier variables relevant to various transactions are stored ina memory block (memory blocks) of a flash type memory device, which is(are) reserved therefor. In addition, each memory block of the flashtype memory device, which houses payload data to be updated inconnection with a transaction, contains memory-block specific statusinformation regarding that particular memory block. This statusinformation expresses whether the updating operation of control andpayload data present in the examined memory block is unfinished orfinished.

When a new transaction is started, the identifier variable relevant tothis particular transaction is added to the list of identifier variablesfor active transactions. The discussed list has been stored in one ormore memory blocks of a flash type memory device reserved therefor. Oncea transaction has been concluded, the identifier variable relevant tothe discussed transaction is deleted from said list. Hence, suchidentifier variable are used for maintaining a status bookkeeping fortransactions, which expresses on-going transactions in real time. Eachchange in a list of identifier variables for active transactionsrequires one writing operation and the erasion of a memory block. Thus,every transaction requires two writing operations and two erasions for amemory block used for storing the identifier variable of saidtransaction.

An individual memory block in a flash type memory device survives alimited number of writing operations. In other words, the memory blockwears down as writing operations are repeated a sufficient number oftimes. When even one of the memory blocks of a memory device is faulted,a replacement of the entire memory device is generally inevitable.Moreover, frequently repeated writing operations, for example inconnection with semiconductor flash memory circuits, reduce the numberof free memory blocks. Clearing a memory block in a semiconductor flashmemory circuit is a considerably slower procedure than readinginformation from a memory block. In the event that a change needs to bedone in information present in a given memory block, this particularmemory block must be first cleared, followed by writing the changedinformation. The resulting speed problem can be solved in such a waythat the changed data is written in another, previously cleared memoryblock, whereby the memory block that was in service before need not becleared until after the file update. However, the result of frequentlyrepeated clearing and writing operations is that there are a largenumber of memory blocks currently in a clearing process or waiting for aclearing process at any given time, thus reducing the number of memoryblocks available for service.

SUMMARY OF THE INVENTION

The invention relates to a method intended for the execution oftransactions relevant to information to be stored in a flash type memorydevice, said method enabling the elimination or alleviation oflimitations and drawbacks existing in the prior art. The inventionrelates also to a recovery method associated with said method forrecovering from a system error that has taken place during atransaction. The invention relates further to an arrangement intendedfor processing transactions relevant to information to be stored in aflash type memory device, said arrangement enabling the elimination oralleviation of limitations and drawbacks existing in the prior art. Theinvention relates also to a computer program, which comprisesprogram-equipped elements for processing transactions of information tobe stored in a flash type memory device so as to enable the eliminationof alleviation of limitations and drawback existing in the prior art.

It has been surprisingly discovered in this invention that memory-blockspecific status information can be used not only-for the management ofpayload data present in a memory block but also for the management of anentire transaction. Thus, a need to conduct a separate statusbookkeeping of transactions will be avoided.

The invention provides a means of attaining the following benefits:

-   -   saving the storage capacity of a flash type memory device as        separate status bookkeeping of transactions is not needed,    -   reducing the number of updating operations needed in a        transaction as status bookkeeping of transactions need not be        updated, and    -   reduction of updating operations increases the service life of a        flash type memory device and reduces its power consumption.

A method of the invention for executing a transaction regardinginformation to be stored in a flash type memory device is characterizedin that the method comprises:

-   -   executing a payload data writing operation relevant to said        transaction into a memory block of said flash type memory        device,    -   setting up memory-block specific status information of said        memory block to express that said transaction is in a commitment        process, and    -   processing the payload data written in said memory block into        valid payload data.

A recovery method of the invention for recovering from a system erroroccurred during a transaction in equipment based on a flash type memorydevice is characterized in that the recovery method comprises:

-   -   reading memory-block specific status information regarding a        memory block of said flash type memory device,    -   determining whether said memory-block specific status        information expresses that said transaction is in a commitment        process, and    -   processing the payload data present in said memory block into        valid payload data in response to the condition in which said        memory-block specific status information expresses that said        transaction is in a commitment process.

An arrangement of the invention for processing a transaction regardinginformation to be stored in a flash type memory device is characterizedin that the arrangement comprises management media, which are linked tosaid flash type memory device and which are adapted to:

-   -   execute a payload-data writing operation relevant to said        transaction into a memory block of said flash type memory        device,    -   set up memory-block specific status information of said memory        block to express that said transaction is in a commitment        process,    -   read the memory-block specific status information of said memory        block and determine whether said memory-block specific status        information has been set up to express that said transaction is        in a commitment process, and    -   process the payload data written in said memory block into valid        payload data in response to the condition in which said        memory-block specific status information has been set up to        express that said transaction is in a commitment process.

A computer program of the invention for processing a transactionregarding information to be stored in a flash type memory device ischaracterized in that the computer program comprises:

-   -   program elements for instructing a processing unit to execute a        payload-data writing operation relevant to said transaction into        a memory block of said flash type memory device,    -   program elements for instructing the processing unit to set up        memory-block specific status information of said memory block to        express that said transaction is in a commitment process,    -   program elements for instructing the processing unit to read the        memory-block specific status information of said memory block        and to determine whether said memory-block specific status        information has been set up to express that said transaction is        in a commitment process, and    -   program elements for instructing the processing unit to process        the payload data written in said memory block into valid payload        data in response to the condition in which said memory-block        specific status information has been set up to express that said        transaction is in a commitment process.

Various embodiments of the invention are characterized by what ispresented in the dependent claims.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described in more detail with reference topreferred exemplary embodiments and to the accompanying figures, inwhich

FIG. 1 shows an arrangement according to one embodiment of the inventionfor processing a transaction of information to be stored in a flash typememory device,

FIG. 2 shows an arrangement according to one embodiment of the inventionfor processing a transaction of information to be stored in a flash typememory device,

FIG. 3 shows a method according to one embodiment of the invention in aflowchart for executing a transaction of information to be stored in aflash type memory device, and

FIG. 4 shows a recovery method according to one embodiment of theinvention in a flowchart for recovering from a system error occurredduring a transaction in equipment based on a flash type memory device.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

FIG. 1 shows an arrangement according to one embodiment of the inventionfor processing a transaction of information to be stored in a flash typememory device 101. The arrangement includes management media 102, whichare linked to said flash type memory device 101. The management media102 consist of one or more processors and interface elements foreffecting a data transfer 103 between the flash type memory device andthe management media, as well as a data transfer 104 between themanagement media and external sets of equipment. The management media102 may further house one or more storage elements. The flash typememory device includes memory blocks, of which memory blocks 111-115 areshown in FIG. 1.

In each memory block of the flash type memory device 101 can be storedcontrol data (C) 121-125 for that particular memory block. The controldata C includes a preferably logical memory block identifier. The systemcomprises maintaining an address table, which links the physical addressof each memory block to the logical memory block identifier of thatparticular memory block. This address table can be maintained forexample in an internal scratch pad memory of the management media 102 orin such a memory block of the flash type memory device which has itsphysical address in all conditions available for the management media.In each memory block can be stored payload data (D) 141-145 andmemory-block specific status information (S) 131-135.

The status information S enables expressing that:

-   -   payload data present in a memory block consists of valid payload        data, or    -   payload data present in a memory block is dirty, or    -   payload data present in a memory block is correct, or    -   payload data present in a memory block is relevant and, in        addition, the transaction is in a commitment process.

For example, the changed balance information of a bank account, whichhas been stored in a flash type memory device, but the transactionprocessing an account entry relevant thereto being still unfinished,represents payload data which is correct but not valid. The transactionmay be unfinished for example for the reason that the account entryrelevant to the change of balance information has not yet been stored inthe flash type memory device.

The management media 102 are adapted to execute a payload-data D writingoperation relevant to a transaction into a memory block of the flashtype memory device 101, to set up the memory-block specific statusinformation S of said memory block to express that said transaction isin a commitment process, to read the memory-block specific statusinformation S of said memory block and to determine whether saidmemory-block specific status information S has been set up to expressthat said transaction is in a commitment process, and to process thepayload data D written in said memory block into valid payload data inresponse to the condition in which said memory-block specific statusinformation S has been set up to express that said transaction is in acommitment process.

First, the operation of a system according to the embodiment of theinvention shown in FIG. 1 will be discussed in reference to a simplesituation, in which a transaction only involves writing payload data tobe updated in connection with the transaction in just one memory block.It is assumed that, at the start of a transaction, the memory block 111is not in active service and thus available for writing operations. Inother words, the memory block 111 is free as the transaction is started.It is also assumed that no changes are needed in memory block controldata 121. Without any general restriction, it can be assumed that thepayload data to be updated in the transaction is written in the memoryblock 111. Payload data 141 is written in the memory block 111 by themanagement media 102. The payload data 141 written in the memory block111 can be intended for replacing payload data present in some othermemory block, or the payload data 141 may consist of payload data justto be added, in which case it is not substituted for payload datapresent in any other memory block. The transfer to a transactioncommitment process is implemented in such a way that, for statusinformation 131, the management media write a value which expresses thatthe transaction is in a commitment process. This is followed byprocessing the payload data 141 present in the memory block 111 intovalid payload data, which possibly replaces some older payload datapresent in any other memory block. This concludes the transaction.Various options for carrying out the validation of payload data shall bediscussed later in this document.

Next, a situation will be discussed, in which a serious system erroroccurs before the payload data 141 is processed into valid payload data.In a recovery process following a serious system error, the statusinformation 131 of the memory block 111 is read by the management media102. In the event that the status information 131 expresses that thetransaction has reached a commitment process, there is adequatecertainty about the payload data 141 present in the memory block 111having been successfully updated. Thus, the payload data 141 present inthe memory block 111 is processed into valid payload data, whichpossibly replaces some older payload data present in any of the othermemory blocks. In the event that the status information 131 does notindicate that the transaction has reached a commitment process, there isa risk of the payload present in the memory block 111 not beingsuccessfully updated. In this case, the transaction is cancelled and inthe situation, in which the payload data 141 written in the memory block111 is intended for replacing some older payload data present in any ofthe other memory blocks, said older payload data present in anothermemory block retains its status as valid payload data.

Next, the operation of a system according to the embodiment of theinvention shown in FIG. 1 will be discussed in reference to a simplesituation, in which a transaction involves writing payload data to beupdated in connection with the transaction in more than one memory blockof a flash type memory device. Without any general restriction, it canbe assumed that payload data to be updated in a transaction is writtenin memory blocks 112, 113 and 114. Said memory blocks 112, 113 and 114are presumed free as the transaction starts. Without any generallimitation, it can be assumed that payload data is written first in thememory block 112, next in the memory block 1 13, and finally in thememory block 114. It is also assumed that no changes are required forcontrol data C of the memory blocks.

Payload data 142 to be updated is written in the memory block 112 by themanagement media 102. Then, for status information 132, the managementmedia 102 write a value which expresses that the payload data 142present in the memory block 112 is correct. The payload data 142 in thememory block 112 is correct, but the transaction cannot be transferredto a commitment process as yet, because the writing operations into thememory blocks 113 and 114, included in said transaction, are yet to becarried out. Payload data 143 to be updated is written in the memoryblock 113 by the management media 102. Thereafter, for statusinformation 133, the management media 102 write a value which expressesthat the payload data 143 present in the memory block 113 is correct.Payload data 144 to be updated is written in the memory block 114 by themanagement media 102. After this, the payload data present in all memoryblocks 112, 113 and 114 is correct, enabling a transfer of thetransaction to a commitment process.

The management media 102 are adapted to transfer the discussedtransaction to a commitment process by setting such a value for thememory-block specific status information 132 and/or 133 and/or 134 of atleast one memory block 112 and/or 113 and/or 114 which expresses thatthe transaction is in a commitment process. In the event that the statusinformation of the last written memory block 114 is not set up toexpress that the transaction is in a commitment process, the statusinformation of the memory block 114 must be set up to express that thepayload data 144 present in the memory block 114 is correct. It shouldbe noted that status information, which expresses that a transaction isin a commitment process, expresses also at the same time that payloaddata stored in a memory block is correct.

This is followed by processing the payload data 142, 143 and 144 presentin each memory block 112, 113 and 114 into valid payload data, whichpossibly replaces older payload data present in any other memory block.Thus, the transaction is concluded. The situation can be for examplesuch that the payload data 142 present in the memory block 112 replacesthe payload data 141 present in the memory block 111, the payload data144 present in the memory block 114 replaces payload data 145 present ina memory block 115, and the payload data 143 present in the memory block113 is just payload data to be added, in which case it does not replacepayload data present in any of the other memory blocks. Various optionsfor carrying out the validation of payload data will be discussed laterin this document.

In the following, a situation will be discussed, in which a serioussystem error occurs before all of the payload data 142, 143 and 144written in a transaction has been processed into valid payload data. Inthe recovery process following a serious system error, the managementmedia 102 read the sets of status information regarding the memoryblocks of a flash type memory device. As long as the memory-blockspecific status information of at least one memory block expresses thatthe transaction has reached a commitment process, there is providedsufficient certainty that the group of memory blocks, constituted bythose memory blocks whose status information expresses that thetransaction is in a commitment process and/or the data contained in thediscussed memory block is correct, encompasses all those memory blocksinto which the writing of payload data has been desired in thetransaction. Thus, the payload data present in each memory block of saidgroup is processed into valid payload data, which possibly replacesolder payload data present in any of the other memory blocks. In theevent that the memory-block specific status information of even a singlememory block does not express that the transaction has reached acommitment process, there is a risk of said group of memory blocks notencompassing all those memory blocks into which the writing of payloaddata has been desired. Hence, the system error has created a situationthat no writing at all has been managed into some memory blocks and/orthe writing into some memory block has stopped in the middle of it. Inthis case, the transaction is cancelled, and in a situation in whichpayload data written in one of the memory blocks has been intended toreplace older payload data present in another memory block, said olderpayload data present in said another memory block retains its status asvalid payload data.

Subsequently in this document, those memory blocks of a flash typememory device, whose memory-block specific status information is usedfor expressing a transaction commitment process, shall be referred to asexpressive memory blocks. Those memory blocks, in which the transactioncomprises writing payload data to be updated, shall be referred to asupdatable memory blocks. Preferably, just one of the updatable memoryblocks is selected to serve as an expressive memory block.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to select an expressive memory block tobe the updatable memory block with the smallest physical address. Inaddition, the management media 102 are adapted to set up thememory-block specific status information of an expressive memory blockin two operations by first setting up the status information to expressthat payload data present in the expressive memory block is correct, andthereafter, when payload data present in all other updatable memoryblocks is correct as well, by setting up said status information toexpress that the transaction is in a commitment process. Provided thatthe recovery process subsequent to a system error comprises reading thememory blocks in an ascending sequence of physical addresses startingfrom the smallest physical address, this embodiment of the inventionoffers the advantage that, finding an expressive memory block, whichindicates that the transaction is in a commitment process, provides acertainty that all other memory blocks, in which data has been writtenin the transaction, can be located after finding the expressive memoryblock.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to select an expressive memory block tobe the updatable memory block with the greatest physical address. Inaddition, the management media 102 are adapted to set up thememory-block specific status information of an expressive memory blockin two operations by first setting up the status information to expressthat payload data present in the expressive memory block is correct, andthereafter, when payload data present in all other updatable memoryblocks is correct as well, by setting up said status information toexpress that the transaction is in a commitment process. Provided thatthe recovery process subsequent to a system error comprises reading thememory blocks in a descending sequence of physical addresses startingfrom the greatest physical address, this embodiment of the inventionoffers the advantage that, finding an expressive memory block, whichindicates that the transaction is in a commitment process, provides acertainty that all other memory blocks, in which data has been writtenin the transaction, can be located after finding the expressive memoryblock.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to select an expressive memory block tobe the updatable memory block with the smallest physical address. Inaddition, the management media 102 are adapted to select the writingsequence of memory blocks such that the expressive memory block is lastto be processed. Thus, the memory-block specific status information ofthe expressive memory block can be set up to indicate that thetransaction is in a commitment process immediately after the desireddata has been written in the expressive memory block.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to select an expressive memory block tobe the updatable memory block which is last to have payload writtentherein in connection with a transaction. Thus, the memory-blockspecific status information of the expressive memory block can be set upto indicate that the transaction is in a commitment process immediatelyafter the desired data has been written in the expressive memory block.The expressive memory block can be any updatable memory block other thanthe one with the smallest or greatest physical address.

Next, an exemplary situation will be discussed, wherein it is desirablein a transaction to write in a memory block 111 of the flash type memorydevice 101 the payload data 141, replacing the older payload data 142stored in a memory block 112 of the flash type memory device 101. Thepayload data 142 constitutes valid payload data as the transactionstarts.

In an arrangement according to one embodiment of the invention, thecontrol data C stored in each memory block contains a cyclic ageindicator and the management media 102 are adapted to determine anupdated value for the cyclic indicator, which in the sequence of apreset rule follows the value of a cyclic age indicator present in thememory block 112, and to write, prior to a transfer of the transactionto a commitment process, said updated value of the cyclic age indicatorinto the memory block 111. Updating said cyclic age indicator canproceed for example in such a way that the cyclic age indicator has itsvalue incremented by one as the transaction begins and, upon reaching apreset final value, the cyclic age indicator will be set to a presetinitial value. Hence, each transaction has a certain cyclic ageindicator value.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to set, prior to a transaction transferto a commitment process, a logical memory block identifier contained inthe control data 121 of the memory block 111 to have the same value asthat of a logical memory block identifier of the memory block 112. Bymeans of logical memory block identifiers, the management media 102 areadapted to determine which memory blocks contain mutual matching newerand older payload data, such as the memory blocks 111 and 112 in thisparticular exemplary case.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to write the control data C into amemory block prior to setting up the memory-block specific statusinformation to express that payload data present in the memory block iscorrect. Hence, the memory-block specific status information, whichindicates that the payload data is correct, indicates also that thecontrol data is correct.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to write, prior to a transactiontransfer to a commitment process, in the control data C of each memoryblock a transaction identifier capable of explicitly identifying theon-going transaction. Thus, the flash type memory device will have acapability of executing concurrently several parallel transactions. Themanagement media 102 are adapted, on the basis of said transactionidentifier, to determine a transaction under which a given memory blockis operated.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to write memory-block specific statusinformation S in a storage space subsequent to information T to bewritten in said memory block. The storage space subsequent toinformation T refers to an area in the address space of said memoryblock, which in the ascending sequence of physical addresses followsthat area in the address space of said memory block in which theinformation T is stored. This enables writing the information T and thememory-block specific status information S in a single session one afterthe other and the correctness of the status information S serves ascertifier that writing of the information T has been successful.

In an arrangement according to one embodiment of the invention, theinformation T is a transaction identifier.

In an arrangement according to one embodiment of the invention, theinformation T represents header information of said memory block. Thememory block header information consists typically of control data C.

In an arrangement according to one embodiment of the invention, theinformation T represents all other information to be written in saidmemory block except said status information.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to express, by means of thememory-block specific status information S, the following possibleconditions:

-   -   A: memory block is free for writing,    -   B: payload data present in memory block is correct,    -   C: transaction is in a commitment process,    -   D: payload data present in memory block is valid, and    -   E: payload data present in memory block is dirty.

In an arrangement according to one embodiment of the invention, a statusA indicates that a memory block in a semiconductor flash memory circuitis in a condition, in which all bits of the memory block have a commonvalue, which is usually ‘1’. Each bit of the memory block can bethereafter be changed for another value, which is usually ‘0’. Afterthis, the only way of changing the value of a discussed bit is toinitialize the entire memory block clear again. The management media 102are adapted to subject a memory block in status E to an initializationoperation, whereby said memory block proceeds to status A.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to implement any of the followingstatus transitions: from status A to status B, from status B to statusC, from status C to status D, and from status D to status E, by changingthe value of just one bit in a bit vector representing said memory-blockspecific status information. Thus, for example, a transition from statusB (payload data in memory block is correct) to status C (transaction isin a commitment process) is atomaric such that the status transitioneither occurs completely or fails to occur at all. A partial occurrenceof the status transition, for example as a result of a system error, isnot possible as the value of an individual bit either changes or doesnot change. The conditions A, B, C, D and E can be presented for exampleby the following, status-information representing bit vectors:

-   A: 1111 (memory block is free for writing)-   B: 0111 (payload data in memory block is correct)-   C: 0011 (transaction is in a commitment process)-   D: 0001 (payload data in memory block is valid)-   E:***0 (payload data in memory block is dirty).-   wherein ‘*’ is a wildcard allowed to be either ‘0’ or ‘1’.

The status transition from status A to status D is not atomaric. Becauseof a system error, for example, it is possible that a desired statustransition from status A to status D be executed only partially, suchthat the only bit to change from one to zero is the one second from theleft in the status information. This means that a faulty statustransition has occurred from status B to status C. However, this is nota problem as long as the condition applied in the recovery process issuch that the status information of at least one memory block mustexpress that the transaction is in a commitment process. Consequently,the situation, in which the status information of two memory blocksexpresses that the transaction is in a commitment process, does notcause a problem.

The above-described bit vector presentation of status information alsoenables a status transition from any of states A-D to status E to beatomaric.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to use the memory blocks of the flashtype memory device 101 as a recording memory for transient informationin the processing of a transaction. In order to illustrate the operationof this embodiment, an exemplary situation is examined, in which payloaddata 141 needs to be written in a memory block 111 in a transaction,replacing older payload data 142 stored in a memory block 112. Thepayload data 142 constitutes valid payload data as the transactionstarts. After the payload data 141 has been written in the memory block111, a situation will arise in which said payload data must be changed.Without any general limitation, it can be assumed that a memory block113 is free for writing. The management media 102 are adapted to set thestatus information of the memory block 111 to express that the payloaddata present in the memory block 111 is dirty, to write into the memoryblock 113 the changed payload data 141, which is represented by payloaddata 143, and to set the status information of the memory block 113 toexpress that the payload data present in the memory block 113 iscorrect.

Discussed in the following is the validation of payload data in anexemplary situation, in which payload data 141 has been written into amemory block 111 in a flash type memory device 101, replacing olderpayload data 142 stored in a memory block 112 of the flash type memorydevice 101. The payload data 142 constitutes valid payload data as thetransaction starts.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to set up in a first operation thememory-block specific status information of the memory block 112 toexpress that the older payload data 142 present in the memory block 112is dirty, and in a second operation to set up the memory-block specificstatus information of the memory block 111 to express that the payloaddata 141 present in the memory block 111 is valid, wherein said firstoperation precedes said second operation.

Considered now is a situation, in which a serious system error occursafter the first operation and before the second operation. In this case,the recovery process following the system error starts from a status inwhich the payload data 142 of the memory block 112 is dirty and thepayload data 141 of the memory block 111 is correct. Thus, in therecovery process, the transaction continues as if the payload data 141written in the memory block 111 were all payload data to be added, notreplacing payload data present in any of the other memory blocks. Thepayload data 142 present in the memory block 112 is overlooked in therecovery process as it is dirty according to the status information ofthe memory block 112.

In an arrangement according to one embodiment of the invention, themanagement media 102 are adapted to set up in a first operation thememory-block specific status information of the memory block 111 toexpress that the payload data present in the memory block 111 is valid,and in a second operation to set up the memory-block specific statusinformation of the memory block 112 to express that the payload datapresent in the memory block 112 is dirty, wherein said first operationprecedes said second operation. Considered now is a situation, in whicha serious system error occurs after the first operation and before thesecond operation. In this case, the recovery process following thesystem error starts from a status in which the payload data 141 of thememory block 111 is already valid, but the payload data 142 of thememory block 112 is also valid. In order to work out such conflictsituation, the management media 102 are adapted, in the arrangementaccording to this embodiment of the invention, to read the value of acyclic age indicator in the memory block 111, to read the value of acyclic age indicator in the memory block 112, to set up the statusinformation 132 of the memory block 112 to express that the payload data142 is dirty, in response to the condition in which the cyclic ageindicator of the memory block 111 has a value which in the sequence of apreset rule is subsequent to the value of the cyclic age indicator inthe memory block 112, and to set up the status information 131 of thememory block 111 to express that the payload data 141 is dirty, inresponse to the condition in which the cyclic age indicator of thememory block 112 has a value which in the sequence of a preset rule issubsequent to the value of the cyclic age indicator in the memory block111.

In an arrangement according to one embodiment of the invention, themanagement media 102 comprise at least one programmable processor. Themanagement media 102 are adapted to implement the above-describedoperations by means of a readable computer program of said processor,which contains program elements such as subprograms, functions and datastructures for instructing said processor to execute the above-describedoperations.

In an arrangement according to one embodiment of the invention, themanagement media 102 comprise at least one application specificintegrated circuit (ASIC). The management media 102 are adapted toimplement the above-described operations by means of interconnectionsbetween the logic ports, internal storage elements and timing devices ofsaid application specific integrated circuit.

FIG. 2 shows an arrangement according to one embodiment of the inventionfor processing a transaction regarding information to be stored in aflash type memory device 201. The arrangement includes management media202, which are linked to said flash type memory device 201. Themanagement media 202 are adapted to execute a payload data writingoperation relevant to said transaction into a memory block of said flashtype memory device, to set up memory-block specific status informationof said memory block to express that said transaction is in a commitmentprocess, to read the memory-block specific status information of saidmemory block and to determine whether said memory-block specific statusinformation has been set up to express that said transaction is in acommitment process, and to process the payload data written in saidfirst memory block into valid payload data, in response to a situationin which said memory-block specific status information has been set upto express that said transaction is in a commitment process. Thearrangement includes a buffer memory medium 203 adapted to store theinformation relevant to said transaction. The management media 202 areadapted to read said buffer memory medium 203 for the information, thewriting of which into the flash type memory device 201 is desired insaid transaction.

In an arrangement according to one embodiment of the invention, themanagement media 202 are adapted to execute parallel transactions in thebuffer memory medium 203, whereby just one transaction needs to be runin the flash type memory device 201. Transactions can be performed inthe buffer memory medium 203 the same way as in a flash type memorydevice. The buffer memory medium can be provided with storage-areaspecific status variables in a way consistent with sets of memory-blockspecific status information used in a flash type memory device. Thestorage area of a buffer memory refers to a section of storage space inthe buffer memory, the information stored therein being managed as asingle entity in a way consistent with information stored in a givenmemory block of a flash type memory device.

In an arrangement according to one embodiment of the invention, thebuffer memory is a dynamic RAM memory (Random Access Memory).

FIG. 3 shows in a flowchart a method according to one embodiment of theinvention for executing a transaction relevant to information to bestored in a flash type memory device. An operation 301 comprisesexecuting a payload data writing operation relevant to said transactioninto a memory block in a flash type memory device. Provided that saidmemory block was not the last memory block to be written, the processmoves to an operation 302, in which memory-block specific statusinformation S of said memory block is set up to express that the payloaddata of said memory block is correct (CORRECT). The process returns fromoperation 302 to operation 301, in which payload data is written in anext memory block to be processed. In the event that the memory block isthe last memory block to be written, the process moves to an operation303, in which status information S of at least one memory block, whichcontains payload data written in the transaction, is set up to expressthat said transaction is in a commitment process (COMMIT). Such a memoryblock functions as an expressive memory block. An operation 304comprises setting up status information S of a memory block, the statusinformation S of which expresses that payload data is correct(S=CORRECT), to express that the payload data is valid (VALID) payloaddata, and setting up status information S_rep of a memory blockcontaining payload data to be replaced (if present) to express that saidpayload data to be replaced is dirty (DIRTY). An operation 305 comprisessetting up status information S of a memory block, the statusinformation S of which expresses that the transaction is in a commitmentprocess (S=COMMIT), to express that the payload data is valid (VALID)payload data, and setting up status information S_rep of a memory blockcontaining payload data to be replaced (if present) to express that saidpayload data to be replaced is dirty (DIRTY).

Preferably, the status information S of just one memory block containingpayload data written in a transaction is set up to express that saidtransaction is in a commitment process (COMMIT).

In a method according to one embodiment of the invention, saidexpressive memory block, among those memory blocks of said flash typememory device in which payload data is written in connection with saidtransaction, is the one with the smallest physical address. In a methodaccording to one embodiment of the invention, said expressive memoryblock, among those memory blocks of said flash type memory device inwhich payload data is written in connection with said transaction, isthe one with the greatest physical address.

In a method according to one embodiment of the invention, saidexpressive memory block, among those memory blocks of said flash typememory device in which payload data is written in connection with saidtransaction, is the last one to have payload data written therein inconnection with said transaction.

In the event that the expressive memory block is not the last memoryblock to be written, the status information of the last written memoryblock is set up to express that the payload data is correct (CORRECT)before the status information of the expressive memory block is set upto express that the transaction is in a commitment status (COMMIT).Hence, the status information of an expressive memory block is set up intwo operations: first said memory-block specific status information isset up to express that the payload data present in the expressive memoryblock is correct (CORRECT) and subsequently said memory-block specificstatus information is set up to express that the transaction is in acommitment process (COMMIT).

In a method according to one embodiment of the invention, the physicaladdress of a memory block is stored in a scratch pad storage inoperation 301 and the beginning of operation 303 comprises selecting thesmallest (or greatest) from among the stored physical addresses ofmemory blocks.

In a method according to one embodiment of the invention, the memoryblock, in which payload data is written in a transaction, has alsowritten therein identification data identifying said transaction. Thus,several parallel transactions can be executed concurrently in a flashtype memory device. The transaction, under which a given memory block isoperated, can be determined on the basis of said identification data.

In a method according to one embodiment of the invention, theidentification data present in a memory block and identifying atransaction is set to zero after the status information of said memoryblock has been set up to express that the payload data present in saidmemory block is valid (VALID) payload data. The knowledge about the factthat the identification data identifying a transaction should be zerowhen the status information expresses that the payload data is valid,can be used for detecting malfunctions.

In a method according to one embodiment of the invention, an operation304, wherein payload data written in a memory block M is processed intovalid payload data, includes the following suboperations:

-   -   Q1: Memory-block specific status information S_rep of a memory        block N, containing payload data to be replaced by payload data        written in a memory block M, is set up to express that the        payload data present in the memory block N is dirty (DIRTY),        whereafter    -   Q2: memory-block specific status information S of the memory        block M is set up to express that the payload data present in        the memory block M is valid (VALID).

In a method according to one embodiment of the invention, the operation305 includes corresponding suboperations Q1 and Q2.

In a method according to one embodiment of the invention, the methodcomprises writing into a memory block M in operation 301 a cyclic ageindicator which expresses that the payload data to be written in thememory block M in the on-going transaction is more recent than thepayload data written in a memory block N in an earlier transaction. Saidcyclic age indicator can be updated for example in such a manner thatthe value of the cyclic age indicator is augmented by one as thetransaction starts and, when the cyclic age indicator reaches a presetfinal value, it will be set to a predetermined initial value. Thus, eachtransaction has a certain cyclic age indicator value.

In a method according to one embodiment of the invention, the operation304, wherein the payload data written in said memory block M isprocessed into valid payload data, includes the following suboperations:

-   -   P1: the memory-block specific status information S of the memory        block M is set up to express that the payload data present in        the memory block M is valid (VALID), whereafter    -   P2: the memory-block specific status information S_rep of the        memory block N, containing the payload data to be replaced by        the payload data written in the memory block M, is set up to        express that the payload data present in the memory block N is        dirty (DIRTY).

In a method according to one embodiment of the invention, the operation305 includes corresponding suboperations P1 and P2.

In a method according to one embodiment of the invention, the methodcomprises writing memory-block specific status information S in astorage space subsequent to information T to be written in said memoryblock. The storage space subsequent to information T refers to an areain the address space of said memory block, which in the ascendingsequence of physical addresses follows that area in the address space ofsaid memory block in which the information T is stored. This enableswriting the information T and the memory-block specific statusinformation S in a single session one after the other and thecorrectness of the status information S serves as certifier that writingof the information T has been successful.

In a method according to one embodiment of the invention, theinformation T is identification data which singles out the on-goingtransaction.

In a method according to one embodiment of the invention, theinformation T represents header information of said memory block. Theheader information of a memory block consists typically of control dataC to be stored in the memory block.

In a method according to one embodiment of the invention, theinformation T represents all other information to be written in saidmemory block except said status information.

In a method according to one embodiment of the invention, thememory-block specific status information S expresses one of thefollowing conditions:

-   -   FREE: memory block is free for writing,    -   CORRECT: payload data in memory block is correct,    -   COMMIT: transaction is in a commitment process,    -   VALID: payload data in memory block is valid, and    -   DIRTY: payload data in memory block is dirty.

In a method according to one embodiment of the invention, any of thefollowing status transitions: from status FREE to status CORRECT, fromstatus CORRECT to status COMMIT, from status COMMIT to status VALID, andfrom status VALID to status DIRTY, is implemented by changing the valueof just one bit in a bit vector representing said memory-block specificstatus information.

FIG. 4 shows in a flowchart a recovery method according to oneembodiment of the invention for recovering from a system error occurredduring a transaction in equipment based on a flash type memory device.An operation 401 comprises reading memory-block specific statusinformation S relevant to a memory block of said flash type memorydevice. A decision-making operation 402 comprises detecting whether saidmemory-block specific status information S expresses that saidtransaction is in a commitment process (S =COMMIT). If this is not thecase, the process proceeds to reading status information of the nextmemory block in operation 401. In the event that the memory-blockspecific status information S expresses that said transaction is in acommitment process (COMMIT), the process moves to an operation 403. Theoperation 403 comprises setting up the status information S of a memoryblock whose status information S expresses that the payload data iscorrect (S=CORRECT) to express that the payload data is valid (VALID)payload data, and setting up the status information S_rep of a memoryblock containing payload data to be replaced (if present) to expressthat said payload data to be replaced is dirty (DIRTY). An operation 404comprises setting up the status information S of a memory block whosestatus information S expresses that the transaction is in a commitmentprocess (S=COMMIT) to express that the payload data is valid (VALID)payload data, and setting up the status information S_rep of a memoryblock containing payload data to be replaced (if present) to expressthat said payload data to be replaced is dirty (DIRTY).

Examined now is an exemplary situation in which the status informationof a memory block M expresses that the payload data is valid (VALID) andalso the status information of a memory block N expresses that thepayload data is valid (VALID). The payload data present in one memoryblock M or N is intended for replacing the payload data present in theother memory block N or M but, because of a system error, the statusinformation of the memory block containing payload data to be replacedhas not been set up to express that the payload data is dirty (DIRTY).

A recovery method according to one embodiment of the inventioncomprises:

-   -   reading a cyclic age indicator value from memory block M,    -   reading a cyclic age indicator value from memory block N,    -   in response to the situation in which the cyclic age indicator        of memory block M has a value which in the sequence of a preset        rule is subsequent to the cyclic age indicator value of memory        block N, setting up the status information of memory block N to        express that the payload data present in memory block N is dirty        (DIRTY), and    -   in response to the situation in which the cyclic age indicator        of memory block N has a value which in the sequence of said        preset rule is subsequent to the cyclic age indicator value of        memory block M, setting up the status information of memory        block M to express that the payload data present in memory block        M is dirty (DIRTY).

A computer program according to one embodiment of the invention forprocessing a transaction relevant to information to be stored in a flashtype memory device contains program elements as follows:

-   -   program elements for instructing a processing unit to execute a        payload data writing operation relevant to said transaction into        a memory block of said flash type memory device,    -   program elements for instructing the processing unit to set up        memory-block specific status information of said memory block to        express that said transaction is in a commitment process,    -   program elements for instructing the processing unit to read the        memory-block specific status information of said memory block        and to determine whether said memory-block specific status        information has been set up to express that said transaction is        in a commitment process, and    -   program elements for instructing the processing unit to process        the payload data written in said memory block into valid payload        data in response to the condition in which said memory-block        specific status information has been set up to express that said        transaction is in a commitment process.

Said program elements can be for example subprograms or functions. Saidprocessing unit can be for example a processor included in themanagement medium 102 shown in FIG. 1.

A computer program according to one embodiment of the invention isstored in a readable recording medium of the processing unit, such asfor example on an optical disk (Compact Disk).

As obvious for a person skilled in the art, the invention and itsembodiments are not limited to the foregoing exemplary embodiments, butthe invention and its embodiments can be subjected to a multitude ofmodifications within the scope of the independent claim.

The invention claimed is:
 1. A method for executing a transactionregarding information to be stored in a flash type memory device, themethod comprising: executing a payload data writing operation relevantto said transaction into a first memory block of said flash type memorydevice, setting up memory-block specific status information of saidfirst memory block to express that a) payload data written in said firstmemory block is relevant and b) said transaction is in a commitmentprocess, and processing the payload data written in said first memoryblock into valid payload data in response to a condition that saidmemory-block specific status information has been set up to express thata) the payload data written in said first memory block is relevant b)said transaction is in a commitment process.
 2. The method as set forthin claim 1, wherein said first memory block, among those memory blocksof said flash type memory device that the payload data is written inconnection with said transaction, is the one with a smallest physicaladdress.
 3. The method as set forth in claim 1, wherein said firstmemory block, among those memory blocks of said flash type memory devicethat the payload data is written in connection with said transaction, isthe one with a greatest physical address.
 4. The method as set forth inclaim 2, wherein said memory-block specific status information is set upin two operations: first said memory-block specific status informationis set up to express that the payload data present in said first memoryblock is correct, and subsequently said memory-block specific statusinformation is set up to express that said transaction is in acommitment process.
 5. The method as set forth in claim 1, wherein saidfirst memory block, among those memory blocks of said flash type memorydevice that the payload data is written in connection with saidtransaction, is a last one to have payload data written therein inconnection with said transaction.
 6. The method as set forth in claim 1,wherein in said first memory block is written identification dataidentifying said transaction.
 7. The method as set forth in claim 1,wherein in said first memory block is written a cyclic age indicatorexpressing that the payload data present in said first memory block ismore recent than the payload data present in a second memory block ofsaid flash type memory device.
 8. The method as set forth in claim 7,wherein the operation, wherein the payload data written in said firstmemory block is processed into valid payload data, contains thefollowing suboperations: setting up the memory-block specific statusinformation of said first memory block to express that the payload datapresent in said first memory block is valid, followed by setting up thememory-block specific status information of said second memory block toexpress that the payload data present in said second memory block isdirty.
 9. The method as set forth in claim 1, wherein the operation ,wherein the payload data written in said first memory block is processedinto valid payload data, contains the following suboperations: settingup the memory-block specific status information of a second memory blockof said flash type memory device to express that the payload datapresent in said second memory block is dirty, followed by setting up thememory-block specific status information of said first memory block toexpress that the payload data present in said first memory block isvalid.
 10. The method as set forth in claim 1, wherein said memory-blockspecific status information is written in said first memory block into astorage space subsequent to other information present in said firstmemory block.
 11. The method as set forth in claim 1, wherein saidmemory-block specific status information is written in said first memoryblock into a storage space subsequent to header information present insaid first memory block.
 12. The method as set forth in claim 6, whereinsaid memory-block specific status information is written in said firstmemory block into a storage space subsequent to the identification dataidentifying said transaction.
 13. The method as set forth in claim 1,wherein said memory-block specific status information expresses one ofthe following conditions: A: said first memory block is free forwriting, B: payload data present in said first memory block is correct,C: said transaction is in a commitment process, D: payload data presentin said first memory block is valid, and E: payload data present in saidfirst memory block is dirty.
 14. The method as set forth in claim 13,wherein any of the following status transitions: from status A to statusB, from status B to status C, from status C to status D, and from statusD to status E, is implemented by changing a value of just one bit in abit vector representing said memory-block specific status information.15. A recovery method for recovering from a system error occurred duringa transaction in equipment based on a flash type memory device, therecovery method comprising: reading memory-block specific statusinformation regarding a first memory block of said flash type memorydevice, determining whether said memory-block specific statusinformation expresses that a) payload data present in said first memoryblock is relevant and b) said transaction is in a commitment process,and processing the payload data present in said first memory block intovalid payload data in response to a condition that said memory-blockspecific status information expresses that a) the payload data presentin said first memory block is relevant and b) said transaction is in acommitment process.
 16. The recovery method as set forth in claim 15,wherein the recovery method comprises: reading the value of a cyclic ageindicator in said first memory block, reading the value of a cyclic ageindicator in a second memory block of said flash type memory device, inresponse to a condition of the cyclic age indicator of said secondmemory block having a value that in a sequence of a preset rule issubsequent to the value of the cyclic age indicator in said first memoryblock, setting up the status information of said first memory block toexpress that the payload data present in said first memory block isdirty, and in response to a condition of the cyclic age indicator ofsaid first memory block having a value that in the sequence of a presetrule is subsequent to the value of the cyclic age indicator in saidsecond memory block, setting up the status information of said secondmemory block to express that the payload data present in said secondmemory block is dirty.
 17. An arrangement for processing a transactionregarding information to be stored in a flash type memory device,wherein the arrangement comprises management media, the management mediaare linked to said flash type memory device and which are adapted to:execute a payload-data writing operation relevant to said transactioninto a first memory block of said flash type memory device, set upmemory-block specific status information of said first memory block toexpress that a) payload data written in said first memory block isrelevant and b) said transaction is in a commitment process, read thememory-block specific status information of said first memory block anddetermine whether said memory-block specific status information has beenset up to express that a) the payload data present in said first memoryblock is relevant and b) said transaction is in a commitment process,and process the payload data present in said first memory block intovalid payload data in response to a condition of said memory-blockspecific status information having been set up to express that a) thepayload data present in said first memory block is relevant and b) saidtransaction is in a commitment process.
 18. The arrangement as set forthin claim 17, wherein, among those memory blocks of said flash typememory device that the payload data is written in connection with saidtransaction, said management media are adapted to select said firstmemory block to be the one with a smallest physical address.
 19. Thearrangement as set forth in claim 17, wherein, among those memory blocksof said flash type memory device that the payload data is written inconnection with said transaction, said management media are adapted toselect said first memory block to be the one with a greatest physicaladdress.
 20. The arrangement as set forth in claim 18, wherein saidmanagement media are adapted to set up in a first operation saidmemory-block specific status information to express that payload datapresent in said first memory block is correct, and in a second operationto set up said memory-block specific status information to express thatsaid transaction is in a commitment process, wherein said firstoperation precedes said second operation.
 21. The arrangement as setforth in claim 17, wherein, among those memory blocks of said flash typememory device that the payload data is written in connection with saidtransaction, said management media are adapted to select said firstmemory block to be a last one to have payload data written therein inconnection with said transaction.
 22. The arrangement as set forth inclaim 17, wherein said management media are adapted to write into saidfirst memory block identification data identifying said transaction. 23.The method as set forth in claim 17, wherein said management media areadapted to determine a value subsequent in a sequence of a preset ruleto the value of a cyclic age indicator present in a second memory blockof said flash type memory device, and to write said sequentiallysubsequent value into said first memory block.
 24. The arrangement asset forth in claim 23, wherein said management media are adapted to setup in a first operation the memory-block specific status information ofsaid first memory block to express that the payload data present in saidfirst memory block is valid, and in a second operation to set upmemory-block specific status information of said second memory block toexpress that payload data present in said second memory block is dirty,wherein said first operation precedes said second operation.
 25. Thearrangement as set forth in claim 17, wherein said management media areadapted to set up in a first operation the memory-block specific statusinformation of a second memory block of said flash type memory device toexpress that payload data present in said second memory block is dirty,and in a second operation to set up the memory-block specific statusinformation of said first memory block to express that the payload datapresent in said first memory block is valid, wherein said firstoperation precedes said second operation.
 26. The arrangement as setforth in claim 17, wherein said management media are adapted to writesaid memory-block specific status information in said first memory blockinto a storage space subsequent to other information present in saidfirst memory block.
 27. The arrangement as set forth in claim 17,wherein said management media are adapted to write said memory-blockspecific status information in said first memory block into a storagespace subsequent to header information present in said first memoryblock.
 28. The arrangement as set forth in claim 22, wherein saidmanagement media are adapted to write said memory-block specific statusinformation in said first memory block into a storage space subsequentto the identification data identifying said transaction.
 29. Thearrangement as set forth in claim 17, wherein said management media areadapted to express, by means of said memory-block specific statusinformation, the following possible conditions: A: said first memoryblock is free for writing, B: payload data present in said first memoryblock is correct, C: said transaction is in a commitment process, D:payload data present in said first memory block is valid, and E: payloaddata present in said first memory block is dirty.
 30. The arrangement asset forth in claim 29, wherein said management media are adapted toimplement any of the following status transitions: from status A tostatus B, from status B to status C, from status C to status D, and fromstatus D to status E, by changing a value of just one bit in a bitvector representing said memory-block specific status information. 31.The arrangement as set forth in claim 23, wherein said management mediaare adapted to: read the value of a cyclic age indicator in said firstmemory block, read the value of a cyclic age indicator in said secondmemory block, set up the status information of said second memory blockto express that the payload data present in said second memory block isdirty, in response to a condition of the cyclic age indicator of saidfirst memory block having a value that in the sequence of said presetrule is subsequent to the value of the cyclic age indicator in saidsecond memory block, and set up the status information of said firstmemory block to express that the payload data present in said firstmemory block is dirty, in response to a condition of the cyclic ageindicator of said second memory block having a value that in thesequence of said preset rule is subsequent to the value of the cyclicage indicator in said first memory block.
 32. The arrangement as setforth in claim 17, wherein the arrangement includes a buffer memorymedium adapted to store the information relevant to said transaction,and said management media are adapted to read said buffer memory mediumfor the information to be written onto said flash type memory device insaid transaction.
 33. The arrangement as set forth in claim 17, whereinsaid management media are adapted to use the memory blocks of said flashtype memory device as a recording memory for transient information inthe processing of said transaction.
 34. A non-transitory computerreadable medium encoded with a computer program for processing atransaction regarding information to be stored in a flash type memorydevice, wherein the computer program comprises: program elements forinstructing a processing unit to execute a payload-data writingoperation relevant to said transaction into a memory block of said flashtype memory device, program elements for instructing the processing unitto set up memory-block specific status information of said memory blockto express that a) payload data written in a first memory block isrelevant and b) said transaction is in a commitment process, programelements for instructing the processing unit to read the memory-blockspecific status information of said memory block and to determinewhether said memory-block specific status information has been set up toexpress that a) the payload data present in said first memory block isrelevant and b) said transaction is in a commitment process, and programelements for instructing the processing unit to process the payload datapresent in said memory block into valid payload data in response to acondition in of said memory-block specific status information havingbeen set up to express that a) the payload data present in said firstmemory block is relevant and b) said transaction is in a commitmentprocess.